A key metric of epidemic prevention improved dramatically soon after China launched massive testing and isolation efforts against the coronavirus, according to a study published recently in Science magazine.

Serial intervals, which measure the average time between the onset of symptoms in a chain of people infected by a pathogen, have shrunk substantially from 7.8 days to 2.6 days in around a month in mainland China, driven by intensive non-pharmaceutical interventions, in particular case isolation, the study said.

Benjamin Cowling at the University of Hong Kong and his colleagues compiled a database of 1,407 transmission pairs from Jan. 9 to Feb. 13, when the Chinese city of Wuhan was the epicenter of the country's outbreak.

These findings suggest that the early isolation of cases reduced further transmission, leading to fewer cases and curbing the spread of the disease.

As a result, most of the remaining transmissions occured either before symptoms are apparent or early in the symptomatic phase, while the serial interval shortened, according to the study.

The researchers hope real-time estimation of serial intervals could be used to track the transmission dynamics of the virus.